In a tire processing machine of the kind in which two tire holding means are mutually opposed, for setting the distance between these tire holding means it is known to use a device comprising a framework or a supporting structure and two distance elements attached thereto and outwardly swingable. The spacing elements as such are each formed by an internally screw-threaded member fixedly mounted on the framework, and by a bolt-like spacing element screwed into this screw-threaded member, the bolt being rotated for setting the applicable axial distance between the tire holding means and thus of the corresponding operating position. The rear extremity of a connecting rod rearwardly traversing the cylinder of a pneumatic piston and cylinder unit secured on the machine frame is placed in contact with the impingement surface of an associated spacing element, whereas the forward end of the connecting rod carries tire holding means.
Although this known spacing mechanism provides for setting different distances by means of a single unit formed by the two distance elements, it is expensive in respect of material and production costs because of the comparatively large framework, and furthermore requires a substantial installation space. Another disadvantage is that the cylinder requires a sealed passage at its rear end for passage of the connecting rod and this involves an additional production cost.
Spacing mechanisms comprising a step-like spacing unit are also known, which are internally secured to the machine frame and furthermore comprise a hydraulic cylinder unit operating transversely with respect to a connecting rod carrying the displaceable tire holding means. The spacing unit is displaced by means of the cylinder unit into the vertical position between the tire holding means and the machine frame which determines the required operating position of the tire holding means, whereupon the tire holding means is moved back towards the spacing unit to assume its operating position. In view of its displacing cylinder unit and of its appropriate attachment to the machine frame, this device is also expensive as regards material and production costs.
It is also known that a loose spacing unit may be placed on the displaceable connecting rod and this unit may then be clamped between the tire holding means and the machine frame to set the required operating position. Such spacing units comprise fixed-length spacing elements formed by a pair of bolts held together by means of a handle. Consequently a separate spacing unit is needed for each distance or operating position, so that a set of several spacing units is required for a tire processing machine.
It is an object to devise a spacing device of the kind specified, which is substantially simplified in its structure and may be produced at low cost.